Madonna -- Like a Gym Teacher

11/30/2010 10:45 AM PST BY Johnny Lopez

Madonna took time out from saving the world, making music, studying Kaballah, designing clothes with her daughter and adopting kids to teach a class at her brand new Hard Candy Fitness gym in Mexico City yesterday.

Memberships at Madge's new sweat factory cost about $160 a month.

Keeping up with the 52-year-old Material mom takes a lot of practice ... and a lot of money.